144 THE EVOLUTION THEORY 



the phyletic development also transitions from one kind of action 

 to the other must have taken place. As long as one believes the 

 Lamarckian principle to be really operative one can suppose that 

 actions, which were originally dependent on the will, when they were 

 often repeated, became instinctive, or, in other words, that instincts, 

 many of them at least, are inherited habits. 



I shall endeavour to show later on that this assumption, plausible 

 as it seems at first sight, cannot be correct; but in the meantime 

 I must confine myself to saying that there are a great number of 

 instincts which must be referred to the process of selection, and that 

 the rest can be similarly interpreted in their essentials at least. 



The instinct of self-preservation is universally distributed, and it 

 is exhibited in many animals by flight from their enemies. The hare 

 flees from the fox and from men : the bird flies away at the approach 

 of the cat ; the butterfly flies from even the shadow of the net spread 

 to catch it. These might be regarded as purely conscious actions, and 

 in the case of the hare and the bird experience and will have un- 

 doubtedly some part in them, but even in these the basis of the action 

 is an organic impulse ; this, and not reflection, causes the animal to 

 flee at sight of an enemy. In the butterfly, indeed, this must be 

 purely instinctive, since it is done with the same precision immediately 

 on leaving the pupa state, before the animal has had any experience. 

 But even in the case of the hare and the bird, taking to flight would 

 in most cases come too late if reflection were necessary first ; if it is 

 to be effective it must take place as instantaneously as the shutting of 

 the lids when danger threatens the eye. 



The hermit-crab (Fig. 34, p. 163), which conceals its soft 

 abdomen in an empty mollusc shell, and drags that about with it on 

 the floor of the sea, withdraws with lightning-like rapidity into its 

 house as soon as any suspicious movement catches its eye, and it is 

 very difficult to grip one of its legs with the forceps in time to draw 

 it out of its shell. The same is the case with the so-called Serpulids, 

 worms of the genus tierpula, and its allies; it is not easy to seize 

 them, because, however quick one is with the forceps, their instinct 

 of fugitive self-preservation acts more quickly still, and they shoot 

 back into their protecting tubes before one has had time to grasp 

 them. But this impulse to flee from enemies, though it seems almost 

 a matter of course, is by no means common to all animals, for in quite 

 a large number the instinct of self-preservation finds expression in an 

 exactly contrary manner, namely, in the so-called ' death-feigning,' that 

 is, remaining absolutely motionless in a definite position precisely pre- 

 scribed to the animal by its instinct. In speaking of protective colouring. 



